After years of researching the issue, Rock County will launch an interactive online map within the next month that identifies areas with potentially high levels of groundwater nitrates.

Rock County Board members accepted a $2,500 grant from the National Environmental Health Association on Thursday night. The fellowship has provided some Rock County Public Health Department employees training on data visualization.

Over the past few years, the county has earned several grants to address its dangerously high groundwater nitrate levels, which are some of the highest in Wisconsin.

Rick Wietersen, the environmental health director for Rock County’s Public Health Department, said drinking water with nitrate levels above 10 parts per million can increase the risk of such conditions as blue baby syndrome and may have links to diabetes, thyroid disease and possible birth defects.   


Private wells in several areas in the county have average nitrate levels greater than 10 parts per million, according to the county’s 10-year testing data.

Nitrates are found in fertilizers and food and waste materials. They can leach into groundwater if they are not carried away in runoff or absorbed by plants.

Wietersen said grants like the one accepted Thursday have allowed the county to partner with UW-Whitewater students and the state Department of Health Services to develop an interactive nitrate risk tracking tool.

Nick Zupan, an epidemiologist with the Rock County Public Health Department, said the county applied for its latest grant in the fall and was the only recipient in the country. County officials were able to utilize state Department of Health Services data expertise to build the tool, Zupan said.

Wietersen said the geographic information system-based tool evaluates potential groundwater nitrate risks by considering such factors as fertilizer use, septic densities, geology and irrigation.

He said people can search the data by address. Zupan said the map will identify potential risks but will not necessarily indicate the parts-per-million value of private wells. He said he hopes residents will get their wells tested if their area is at risk.

Once it is available, the map will be found online at gazettextra.com/nitrates.


It is unclear why Rock County has such high nitrate levels.

In 2017, the county formed the Ground Water Nitrate Work Group to research the matter and consider mitigation solutions.

More efficient fertilizer application and observing more closely how rural communities manage their septic systems were among suggestions from the work group, said Nick Baker, a Rock County agriculture agent with UW Extension and a group member.

Baker said the group has also looked at increasing cover crops in agricultural areas to curtail nitrate leaching.

Baker said the county collects data on three test wells on county-owned farmland near the Rock County Jail. He said they are monitoring groundwater and nitrate levels in the well water and trying to find correlations.

This story was changed March 15, 2019, to reflect the following correction:

A story on Page 1A on Friday incorrectly attributed a statement to Rick Wietersen, environment health director for Rock County's Public Health Department. Weitersen said drinking water with high nitrate levels may have links to diabetes, thyroid disease and possible birth defects. UW Extension Agriculture Agent Nick Baker, who is a member of the Rock County Groundwater Nitrate Work Group, said nitrates have been linked to Alzheimer’s disease.

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